• The Transactions of the Korean Institute of Electrical Engineers C
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• v.48 no.3
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• pp.215-220
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• 1999

$SO_2$and CO gas removal characteristics of a wire-to-cylinder type nonthermal discharge plasma reactor in various applied voltage (-dc, ac, fast rising pulse and high frequency pulse) and a crossed dc magnetic field have been investigated. The experiment has been emphasized on the oxidizing characteristics of $SO_2$ and CO gas by $O_3$ and the applying of a crossed magnetic field, which would induce the cyclotronic and drift motions of electrons making the residual time longer in the removal airgap space. And it also would enhance the energy of electrons and the electrophysicochemical actions to remove the pollutant gases effectively. It is found thatthe corona onset voltage and the breakdown voltage were decreased with increasing the crossed magnetic field and decrease initial fed $SO_2$and CO concentration. As a result, a higher ozone generation and $SO_2$ and CO gas removal rate of 20[%] can be obtained with -dc, ac and fast rising pulse corona discharges in the crossed dc current-induced magnetic field. But high frequency pulse didn't show effect in applying of a crossed magnetic field.

• Journal of the Korean Vacuum Society
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• v.18 no.1
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• pp.66-72
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• 2009

The detection methods are required to monitor and diagnose the abnormality on the insulation condition inside a gas-insulated switchgear (GIS). Due to a good sensitivity to the products decomposed by partial discharges (PDs) in $SF_6$ gas, the development of a SWNT gas sensor is actively in progress. However, a few numerical studies on the diffusion mechanism of the $SF_6$ decomposition products by PD have been reported. In this study, we modeled $SF_6$ decomposition process in a chamber by calculating temperature, pressure and concentration of the decomposition products by using a commercial CFD program in conjunction with experimental data. It was assumed that the mass production rate and the generation temperature of the decomposition products were $5.04{\times}10^{-10}$ [g/s] and over 773 K respectively. To calculate the concentration equation, the Schmidt number was specified to get the diffusion coefficient functioned by viscosity and density of $SF_6$ gas instead rather than setting it directly. The results showed that the drive potential is governed mainly by the gradient of the decomposition concentration. A lower concentration of the decomposition products was observed as the sensors were placed more away from the discharge region. Also, the concentration increased by increasing the discharge time. By installing multiple sensors the location of PD is expected to be identified by monitoring the response time of the sensors, and the information should be very useful for the diagnosis and maintenance of GIS.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.48 no.8
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• pp.587-590
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• 1999

In this study, it is the purpose to develope a cheap and compact $CO_2$ laser and to apply 60 Hz AC discharges as a new exciting source. An axial and water cooledtype was adopted as the laser mode. The laser performance characteristics as various parameters, such as gas pressure and discharge current, have been investigated. And the laser output and the efficiency of DC and 60 Hz AC discharge-exciting type have been measured and compared for the different input powers at the static operational pressure. As a result, the case of 60 Hz AC discharge-exciting type, the laser oscillation began at the condition of operational pressure 6 Torr and discharge current 5 mA. A maximum laser output of about 32 W was obtained at an operational pressure of 18 Toorr and a discharge current of 30 mA. In addition, the laser output was saturated from an operational pressure of about 14 Torr and a discharge current of about 20 mA. In this $CO_2$ laser, the laser output of 60 Hz AC discharge-exciting type was slightly higher than that of DC discharge-exciting type. And the laser efficiency was about 10 to 13% for the various operational pressures and the discharge currents.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.15 no.6
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• pp.234-238
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• 2005

Effects of plasma composition, ion flux and ion energy on the etch rate, surface morphology and near surface stoichiometry of a single crystalline $La_3Ga_5SiO_{14}$ wafer have been examined in $Cl_2/Ar$ inductively coupled plasma (ICP) discharges. Maximum etch rate ${\sim}1600{\AA}/min$ was achieved either at relatively high source power $({\sim}1000W)$ or high $Cl_2$ content conditions in $Cl_2/Ar$ discharges. The etched surfaces showed similar or better RMS roughness values than those of the unetched control sample and the near surface stoichiometry was found not to be affected by ICP etching.

• Proceedings of the KIEE Conference
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• 2004.07c
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• pp.1997-1999
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• 2004

In this paper, a novel method has been proposed by use of HY-Pockels sensor for the detection of PD in GITR(Gas Insulated Transformer) in order to improve reliability and to overcome the shortcomings of other techniques which are currently employed. For this work, different types of the test specimen, simulating the winding of the real GITR, have been designed and fabricated to generate the PD. And then, the detection of PD has been realized by conventional methods according to IEC 270 and also the proposed novel sensor as well. Afterwards, their results are well compared to understand the correlation between the nature of the defects in the winding and their PD pattern.

• Journal of the Korea Institute of Building Construction
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• v.13 no.3
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• pp.253-262
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• 2013

The test on the mix of PVA fiber of low carbon inorganic composite as a cement substitute found it to be satisfactory in terms of flexibility and stiffness. The result of the evaluation of the properties of low carbon inorganic panel revealed that the absorptivity was low at 8 to 9%, which is lower than the KS value of 25%. Also, the test on non-combustibility and gas toxicity found that these factors satisfied the decision criteria. In the test on heavy metals discharges, Pb, Cd, Cr6+, Hg, and As were not detected. Regarding far-Infrared emissivity and formaldehyde emission, the substitute was found to be harmless to the human body. Therefore, if the issue of shrinkage, which is a disadvantage of inorganic composites, is addressed, it is judged that it is possible to develop a low carbon inorganic composite panel with better performance.

• 한국연소학회:학술대회논문집
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• 2014.11a
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• pp.383-386
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• 2014

The characteristics of gas free jet flows in laminar with having applied electric fields have been investigated experimentally. A single electrode configuration was adopted such that electric fields were applied directly to nozzle and thus the surrounding could be an infinite ground. The experimental results showed that breakdown point at laminar flow has been measured by varying the applied voltage and frequency of AC. The effect of applying electric fields to free jet flow in laminar was discussed in detail.

• Electrical & Electronic Materials
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• v.4 no.1
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• pp.65-72
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• 1991

본 논문은 전극의 표면상태가 기체방전의 전리성장과 특성에 미치는 영향에 관한 것으로 질소-산소 혼합가스중의 순수전극과 오손전극의 상태에서 전압-전류 특성과 글로우방전 개시전압을 측정하였다. 순수전극의 경우, 압력과 전극간의 거리의 곱이 8(Torr-cm)이하이고 산소의 혼입량이 0.005(%)이하일 때의 전리성장은 암류로부터 안정타운젠트방전을 거쳐 글로우방전으로 이행되었으며 글로우방전 개시전압은 거의 일정하였다. 동일의 전극표면상태에서 조차 방전개시전압은 산소혼입비에 의존하며 방전횟수에 따른 이의 변화는 산소의 함량이 0.1(%)부근에서 크게 나타났다. 방전횟수와 산소혼입량의 증가에 따른 방전개시전압의 상승은 주로 전극표면에서의 산소흡착층의 형성과 부착작용에 의한 NO, $O_{2}$, NO$_{2}$, $O_{3}$와 간은 부이온의 생성에 기인된 것으로 여겨진다.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.14 no.5
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• pp.220-225
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• 2004

Four different Fluorine-based gases ($SF_6/,NF_3, PF_5,\; and \; BF_3$) were examined for high rate Inductively Coupled Plasma etching of Si. Etch rates up to ~8$\mu\textrm{m}$/min were achieved with pure $SF_6$ discharges at high source power (1500 W) and pressure (35 mTorr). A direct comparison of the four feedstock gases under the same plasma conditions showed the Si etch rate to increase in the order $BF_3$ < $NF_3$< $PF_5$ < $SF_6$. This is in good correlation with the average bond energies of the gases, except for $NF_3$, which is the least strongly bound. Optical emission spectroscopy showed that the ICP source efficiently dissociated $NF_3$, but the etched Si surface morphologies were significantly worse with this gas than with the other 3 gases.

• Journal of Electrical Engineering and Technology
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• v.2 no.3
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• pp.396-400
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• 2007

A novel technique has been proposed and related experimental works have been performed in order to detect the partial discharges and the location of the possible defects introduced into the Gas Insulated Switchgear. For this purpose, a prototype HY Pockels sensor has been developed and then employed in order to investigate its field applicability for finding the location of the defects using a 170kV GIS mock-up. Our proposed sensor enables us to measure the electric field variation due to the PD occurrence. In addition, the different PD patterns are observed, which might be dependant on the location and the distance of the sensor with respect to the PD source. Throughout this work, its linear response has been proved to be admissible as a function of the applied voltage. And also the position of the PD source might be distinguished by comparing the PD patterns.